• Understand how ultrasound is used to evaluate the superficial venous system for varicose veins.

• Demonstrate refluxing pathways in the venous system.

• Discuss the role of ultrasound during endovenous ablation for varicose veins

• Describe the appearance of the greater saphenous vein in post-ablation studies

Varicose vein disease is a common medical problem that is associated with multiple symptoms of varying degrees. Many patients seek treatment because the varicosities are cosmetically discomforting; but they also frequently admit to experiencing aching pain, night cramps, heaviness, pressure, swelling and even the chronic skin changes associated with venous insufficiency. In the past, treatment has required surgical ligation and stripping of the GSV (greater saphenous vein). Newer methods of treatment involve an endovascular approach using a tiny catheter rather than surgery. Thermal energy is applied to the vein wall through the catheter by either a laser or radiofrequency device. Both techniques result in a non-thrombotic vein occlusion by heating of the vein wall. Endovenous treatments have the advantage of being minimally invasive with fewer complications, reduced recovery time and decreased cost compared to surgery.

Although a number of options exist for imaging the venous system, ultrasound has evolved as the imaging modality of choice. In the pretreatment venous study, ultrasound is used to map the anatomy, both normal and variant as well as the refluxing pathways. Ultrasound imaging is also an integral tool during the endovenous procedure. It is used to locate the best access site, determine placement of the guidewire and guide the application of tumescent anesthesia. Post-treatment ultrasound studies are used to confirm resolution of the reflux and successful obliteration of the treated vein.

While many sonographers are quite familiar with the anatomy of the deep venous system in the lower extremity, they are often less familiar with that of the superficial venous system. Evaluation for deep vein thrombosis with ultrasound is often well understood, but the method to elicit reflux or map varicose veins is not. Therefore it is essential for sonographers and interpreting physicians to master the specific anatomy, physiology and techniques associated with evaluating venous reflux disease.

Two principal veins form the superficial system of the lower extremity, the GSV (also known as the long saphenous vein) and the LSV (lesser, short or small saphenous vein). They are referred to as truncal veins; and varicosities associated with them are termed truncal varicosities. A number of tributaries and branch veins converge to form these two large trunks. It is important to recognize that variation in the anatomy is common, even from leg to leg.

The GSV begins anterior to the medial malleolus and courses upward along the anteromedial aspect of the calf (Fig 1). It continues along the medial side of the knee and thigh to end in the common femoral vein (CFV). The termination of the GSV into the CFV is known as the saphenofemoral junction (SFJ). From the knee upward, the GSV is usually contained within a fascial envelope that is readily visualized with ultrasound (Fig 2). This envelope consists of the muscular fascia (deep to the GSV) and the saphenous fascia (superficial to the GSV). Recognition of the fascial envelope aids identification of the GSV with ultrasound. The fascial envelope restricts the amount of dilatation the GSV can incur, making it impossible to determine normalcy from size alone. But typically, a normal GSV measures 3-4 mm in the mid thigh. When reflux is present, it is usually larger, but there is no direct association between the size of the GSV and the severity of the disease.

Duplication of the GSV in the upper leg has been reported to occur, but true duplication is probably rare. Accessory saphenous veins may be seen coursing outside the fascial envelope and running parallel to the GSV.

Figure 1 - The GSV is the longest vein in the body. This Logiqview image shows the GSV from the level of the SFJ to the knee.

Figure 2 - Transverse view of the GSV. The bright interfaces of the fascia forming the saphenous compartment are easily recognized on ultrasound (arrows). Identification of its surrounding fascial envelope helps to differentiate the GSV from accessory or tributary veins.

Key anatomy includes the terminal valve, usually located within the junction of the SFJ; and the subterminal valve, usually found just beyond the terminal valve in the GSV. Sometimes more than one subterminal valve is present. These valves are usually easily identified with ultrasound (Fig 3). Reflux through one or more of these valves is the most common cause of varicose veins in the lower extremity.

Figure 3 - Sagittal view of the proximal GSV. The terminal valve (closed arrow) of the GSV is located at the SFJ. The subterminal valve (open arrow) is located about 1 cm distal to the terminal valve.

Before emptying into the CFV, the GSV receives the pudendal, epigastric and circumflex veins. Two important tributaries joining the GSV just below the SFJ are the anterolateral and posteromedial veins (Fig 4). These 2 tributaries are often identified as the source of reflux when the GSV is normal. The epigastric, external pudendal and circumflex tributaries may also be involved in reflux leading to varicose veins.

Figure 4 - Important tributaries of the GSV.

Numerous perforating veins connect the GSV to the deep venous system. The normal flow path in the perforators is from the GSV into the deep system, but flow direction by itself cannot be the sole criteria for abnormalcy. The size of the perforating vein is also important. Those measuring greater than 3.5 mm have been found to be abnormal at least 90% of the time. Reflux through perforators can lead to varicose veins; but often occurs as a result of vein dilatation from pre-existing GSV reflux. The perforating veins course obliquely through the deep fascia connecting the saphenous veins and tributaries to the femoral, popliteal, tibial, peroneal and sinusoidal veins (Fig 5). There are four groups of important perforating veins. These are the Hunterian, Dodd’s, Boyd’s and Cockett’s perforators.

Figure 5 - Perforating vein coursing obliquely from the GSV to the deep system. Color assignment in this case is for red to show flow toward the beam. This indicates an abnormal flow direction in this perforator toward the GSV instead of the deep system.

The LSV is associated with more anatomic variation than the GSV. The LSV begins posterior to the lateral malleolus and quickly moves to the center of the posterior calf where it courses straight upward to the popliteal fossa. In the upper calf it is seen very close to the skin, between two fascial layers, with the gastrocnemius muscle on either side (Fig 6). Sonographically, it is easiest to recognize and follow the LSV in a transverse plane. Normally, the LSV measures about 3 mm or less in the upper calf. The junction of the LSV with the popliteal vein is termed the SPJ (saphenopopliteal junction). This junction is highly variable. Most commonly, the LSV pierces the deep fascia and terminates into the popliteal vein at the level of the popliteal fossa. Otherwise it may not terminate at all, merely branching into multiple small veins that connect with the femoral system. In some cases, the termination of the LSV is into an oblique vessel named the Vein of Giacomini. This vein may drain into the GSV through the posteromedial tributary or alternatively into the deep femoral vein.

The lateral and medial gastrocnemius veins join the popliteal vein at the popliteal fossa and are easily confused with the LSV by ultrasound. However, they can be readily differentiated from the LSV with color Doppler identification of an accompanying artery. The gastrocnemius veins are paired veins that accompany an artery, whereas the LSV is a single vein traveling without an artery (Fig 7). The gastrocnemius veins travel within the muscle in the calf, but the LSV courses above the muscle.

Figure 6 - Transverse view at the popliteal fossa. The lesser saphenous vein is shown in its normal location, sandwiched between 2 fascial layers in this normal patient. The LSV is very superficial and is easily compressed with probe pressure. The gastrocnemius muscles are seen posterior and lateral to the LSV.

Figure 7 - Transverse color Doppler image at the popliteal fossa. The paired gastrocnemius veins are seen on either side of the artery. They are located within the gastrocnemius muscle. The LSV is seen superficialand central to the gastrocnemius veins. This image shows only one set of gastrocnemius veins, but they are located on each side within the muscle. The popliteal vein is not demonstrated in this particular image.

Varicose veins are a common problem, with estimates as high as 30-60% of the population being affected. The incidence increases with advancing age. The disease is more than cosmetic, with most patients reporting symptoms that range from mild to severe. Symptoms include aching pain, burning, cramping, throbbing, leg fatigue, and swelling. Standing for long periods and heat aggravate symptoms. Walking, cool temperatures and elevation improves them. Pregnancy and the menstrual cycle also tend to worsen symptoms.

Varicose veins do not improve over time, rather, without intervention, most varicose veins continue to enlarge, with recruitment of new vessel involvement. Eventually, most people with chronic venous reflux and varicose veins will develop skin changes and swelling, with some progressing to venous ulceration. Deep vein thrombosis is a serious condition that is more common in patients with varicose veins and superficial phlebitis. Fatalities have been reported from rupture of varicose veins with external bleeding.

What causes varicose veins to develop? Healthy veins have a one-way valve that directs blood flow in toward the deep venous system and then up toward the heart and lungs. Blood courses from the superficial veins to the deep venous system through connecting vessels called perforators. The calf muscle pump is the force behind the upward motion of the venous blood column (Fig 8). The contraction of the calf muscle produces a temporary high pressure in the deep venous system that forcefully moves the blood flow. Closure of the valve leaflets keeps the blood from flowing back down the leg. Non-functioning (termed incompetent) valves allow the flow to leak through the valves and reflux down and outward toward the superficial venous system. This, in turn, exposes the superficial veins to the high pressure that is standard within the deep venous system during calf muscle contraction. The pressure in the superficial venous system is normally very low. When exposed to high pressure, superficial veins dilate and become tortuous, creating varicose veins. Varicose veins are actually just normal veins that have dilated due to high pressure.

Figure 8 - As we walk, the muscles in the calf contract, pushing the blood column upwards. With relaxation, healthy valve leaflets close, prohibiting backward flow.

Incompetent valves can occur as a result of several factors. Previous venous thrombosis can damage valves and increase venous pressure through outflow obstruction (if the blood can’t flow up past a thrombus in the deep system, it may be forced into the superficial system). In these patients, it is important not to ablate the GSV as it is an important outflow channel for the leg. Valves may be damaged through trauma. Heredity also plays a role in valve failure. Jobs that require prolonged standing can result in chronic venous distention producing valve failure (if the vein is enlarged, the valve leaflets may not meet when “closed”, allowing reflux). Another important risk factor is pregnancy. Under hormonal influence, valve leaflets soften and vein walls become more distensible. The weight of the enlarging uterus on the veins can increase venous pressure and distention. Advancing age is another risk factor, the veins become weakened and valve failure more common.

Once a single valve becomes incompetent, a high pressure leak is created between the deep and superficial venous system. This causes local dilatation of the superficial vein involved with the leak. As the vein dilates, additional nearby valves fail as their valve leaflets can no longer completely close. This causes further superficial vein dilatation and increased venous pressure. Gradually more and more superficial veins become dilated with increasing varicosities (Fig 9).

Figure 9 - The schematic on the left shows the normal flow direction from the superficial to the deep venous system. On the right, valvular incompetence at the GSV terminal valve leads to reflux with subsequent failure of nearby valves and perforating veins.

Now that we understand how varicose veins are formed, let's find out how to evaluate them with ultrasound. First, we need to know which valves tend to fail. The most common scenario is failure of the terminal valve at the saphenofemoral junction (Fig 10). Competence of the terminal valve with failure of one of the subterminal valves in the GSV is also common. Incompetence at the saphenopopliteal junction occurs less frequently than at the SFJ, but can result in significant varicosities. The major tributaries of the GSV may have incompetent valves leading to varicose veins. The anterolateral and posteromedial tributaries can have significant reflux even with a normal SFJ. In pregnancy, the pudendal tributary may be the source of reflux.

Perforating vein incompetence can cause varicosities, but often occurs as a result of pre-existing superficial vein incompetence. With treatment of the superficial vein, pressure is reduced and incompetent perforators may return to normal function.

A	B	C
Figure 10 - Illustration A depicts failure of the terminal valve at the SFJ. Flow courses up the femoral vein and leaks through an incompetent terminal valve to reflux down the GSV. In illustration B, the terminal valve is competent, but the subterminal valve fails. Reflux is provided through one of the GSV tributaries. Illustration C demonstrates an example of perforator incompetence with competent terminal and subterminal valves. This scenario would result in a segmental section of reflux within the GSV. Alternatively, the GSV may not be involved at all, with reflux occurring through a large tributary such as the anterolateral or posteromedial vein (not shown).

When our patients arrive in ultrasound, we need to question them about their history and symptoms. For example, a family history of varicose veins makes truncal reflux more likely. Then we must look at the leg with the patient standing to see the pattern of varicosities. This physical inspection can provide important clues as to which vessels and sites may be involved with reflux (Fig 11). Dilatation of the GSV from proximal to distal is typical with SFJ incompetence. Varices in the upper thigh, lower abdomen and pelvis are often associated with ilio-femoral vein thrombosis as in May-Thurner syndrome. Dilated veins that are clearly visible on the medial thigh are often superficial tributaries that accept reflux from the GSV. Ultrasound will show the branch arising from the GSV and piercing upward through the superficial fascia. Reflux through the Hunterian perforators in Hunter’s canal may result in visible or palpable varices in the medial aspect of the mid thigh. There is a lot of overlap between the appearances of varicosities and their origins, but a visual inspection is still very helpful.

A	B	C
Figure 11 - The patient in photo A has terminal valve reflux of the GSV, with dilatation of the GSV along its' length and varicosities in the medial calf. The patient in photo B has visible varicose veins in the medial thigh from reflux of a superficial tributary of the GSV. Patient C has a normal GSV with reflux through the anterolateral tributary forming varices on the lateral aspect of the thigh.

Patient Positioning
Patient positioning is very important when evaluating the venous system for reflux. The ultrasound exam may be performed with the patient in a standing or reversed Trendelenburg position (head elevated with feet lowered). If reflux can be obtained in a reversed Trendelenburg position, it may not be necessary to stand the patient for further scanning. If reflux is not apparent with the patient in reverse Trendelenburg, then it is necessary to search for it with the patient standing. This is a more difficult scanning position for the sonographer and care must be taken to adjust the ultrasound control panel and monitor at an appropriate height and angle to avoid excess stress on the sonographers’ neck and shoulder. If the ultrasound bed can be tilted into reversed Trendelenburg, it should be tilted as much as possible while maintaining comfort and security for the patient, at least 30-45 degrees. If the bed cannot be tilted, the exam can be still be performed with the patient head elevated, but this is less desirable and reflux may not be detected until the patient stands. The patient must not be evaluated in a horizontal position as this can lead to misdiagnosis. The purpose of tilting the bed is to increase venous pooling in the legs to improve visualization of the veins. Additionally, the increased pressure associated with venous pooling enhances the demonstration of reflux with Doppler. In fact, with the patient in a horizontal position, even when valves are incompetent, reflux may not be demonstrable with Doppler.

The leg to be examined is rotated out in a slight frog-leg position for evaluation of the SFJ, GSV and deep veins of the thigh. To better visualize the varicosities in the anterior thigh, the leg is rotated back into a supine position. Imaging of the popliteal fossa, posterior thigh and calf is best performed with the patient rolled onto their side, away from the leg to be scanned. This relaxes the leg and permits better visualization of the LSV. When performing ultrasound exams for deep vein thrombosis (DVT), it is usually not necessary to roll the patient to adequately image the popliteal vein, but for reflux exams, this position is very helpful to demonstrate the LSV. The LSV may also be examined with the patient sitting on the bed with the leg dangled over the edge, or in a standing position.

Equipment
A high frequency ultrasound transducer (10-12 MHz) is preferred for imaging the GSV, as it is a superficial vessel. Occasionally, a lower frequency may be needed to better visualize the common femoral vein. Color Doppler is not absolutely necessary for this exam, but is a very helpful tool to quickly demonstrate reflux.

Pretreatment Ultrasound Exam
The purpose of the duplex exam is to determine the source of the reflux causing the varicosities. From this, it can be determined if the patient is a candidate for endovenous ablation therapy. If reflux in the GSV, LSV, or a treatable tributary is found, then a complete scan to rule out DVT must be included in the protocol. A sample protocol is outlined in the table below.

Scanning is begun at the level of the SFJ and the saphenous vein is followed down to the knee or the level of the lowest varicosities. The ultrasound exam includes imaging, compression maneuvers and Doppler analysis. At the terminal valve of the GSV, both the Valsalva maneuver and distal compression can be used to detect reflux. The Valsalva maneuver is not a reliable indicator of reflux beyond a competent terminal valve. It is necessary to use distal limb compression to elicit reflux at all other sites. Sagittal imaging with color Doppler is a useful way to quickly detect the presence of reflux. Upon release of distal compression, the color assignment switches from blue to red (or vice versa depending upon the invert setting). A very brief reversal of color assignment is normal and signifies valve closure, but an extended period of reversal indicates reflux (Fig 12).

Figure 12 - Significant reflux seen with release of distal compression in the GSV at the terminal valve. The normal flow direction is blue and the reflux is color encoded red. Click on the image to view the video clip

Once the reflux has been demonstrated with color flow imaging, a Doppler waveform is obtained to measure the reflux. Reflux lasting over 0.5- 1 seconds is considered abnormal. Although the amount of reflux time can be measured with Doppler, it is not possible to quantify the exact reflux length and velocity as neither the Valsalva maneuver nor compression can be standardized (i.e. the force of the Valsalva maneuver or compression varies, etc.). Nevertheless, distal compression does give satisfactory results (Fig 13). It is necessary to check for reflux along the length of the GSV as well as within the tributary vessels. It is not uncommon to find a competent terminal valve with an incompetent subterminal valve in the GSV (Fig 14), or the GSV may be normal with reflux provided by a large tributary such as the posterolateral vein (Fig 15). The lesser saphenous at the SPJ is also an important site to check for reflux (Fig 16).

Figure 13 -Reflux lasting over 7 seconds in the mid segment of the GSV. Reflux was elicited with release of distal limb compression.

A		B
Figure 14 - Doppler waveforms obtained just beyond the terminal valve in the GSV. Image A was obtained during Valsalva maneuver and shows no reflux. But Image B, obtained with distal limb compression shows significant reflux lasting more than 6 seconds. Since the terminal valve is competent, the Valsalva maneuver is not effective in demonstrating reflux beyond it. With distal compression, reflux is readily demonstrated confirming incompetence of the subterminal valve.

A		B
C
Figure 15 - This patient has a normal GSV with no reflux (A). A large anterolateral vein demonstrates significant reflux lasting over 2 seconds (B). Image C shows the length of the anterolateral tributary with a large varix piercing the superficial fascia and coursing superficially.

A		B
C
Figure 16 - This patient has reflux in the lesser saphenous vein at the popliteal fossa. A transverse view shows a large LSV sandwiched between two fascial layers (A). At least 2 seconds of reflux is apparent with spectral Doppler. In the popliteal fossa, the LSV (closed arrow) is seen surrounded by the fascia. Underneath are the gastrocnemius veins and arteries (open arrow).

After determining the vessel to be ablated, it is evaluated with ultrasound for size, distance from the skin line and tortuosity. Large vessels may require special techniques during the ablation procedure to reduce their size so that the vein wall is closer to the heating device; otherwise complete obliteration of the vein may not occur. Tortuous veins can be difficult to access or to thread with a guidewire. Advance knowledge and mapping of the tortuous segment can aid planning of the interventional procedure. 3D is a handy tool for documenting vessel tortuosity (Fig 17), as the resulting picture is easy to understand. But routine transverse views or cineloop sweeps can be used to document tortuous segments. Sometimes the GSV will course toward the skin through the superficial fascia. The distance from the skin should be measured and documented throughout the length of the vessel to be ablated. Prior to endovenous ablation, the skin can be marked at the point where the vein becomes superficial and the power can be reduced in the ablating device. A tumescent fluid is also injected around the vein and between the vein and skin to act as a buffer to avoid thermal skin injury.

Patients return for a follow-up exam 1 week post ablation. At this exam, the treated vein should be non-compressible. Color Doppler will demonstrate an absence of venous flow within the lumen of the vein. The vein will contain echogenic material. This is not thrombus, but rather thickening of the vein walls obliterating the lumen. At one week, the size of the ablated vein is similar to the pretreated size (Fig 22). Very sensitive color Doppler settings may detect small vessel flow within the thickened vein walls. Spectral Doppler will primarily show low resistance arterial flow from these tiny vessels.

A		B
Figure 22 - Image A is a sagittal color Doppler image at the SFJ obtained one week post ablation. The GSV lumen is filled with echoes representing the thickened vein wall. Color Doppler confirms the absence of venous flow within the GSV lumen. This patient had 2 vessels treated, the GSV and a large adjacent tributary (B). Both vessels are shown to be noncompressible on transverse imaging (arrows).

A		B
Figure 23 - Transverse color and Doppler views of the GSV one week post ablation therapy. With very sensitive color Doppler settings, tiny vessels are seen within the thickened vein wall. Pulsed-wave Doppler shows low resistance arterial waveforms consistent with inflammatory reaction.

It is postulated that this is an inflammatory reaction within the vaso vasorum. This resolves over time and should not be confused with recannalization or failure to obliterate the vein (Fig 23).

Follow-up exams at 3, 6 and 12 months will demonstrate progressive shrinking of the treated vein (Fig 24). After a year or more, the vein has become a fibrous cord and may no longer be detectable by ultrasound.

Figure 24 - Sagittal image of GSV 3 months post ablation therapy. The GSV has become a small, fibrous cord that is a challenge to locate on ultrasound (arrows).

Ultrasound is the key imaging modality for evaluation of varicose veins. It is invaluable for pretreatment assessment of reflux, guidance during endovenous ablation and for follow-up exams. The astute clinical team couples their knowledge of the superficial venous system with today’s advanced ultrasound technology to produce optimal clinical results of endovenous ablation therapy.

1. Weiss RA, Weiss MA: Controlled Radiofrequency Endovenous Occlusion using a Unique Radiofrequency Catheter under Duplex Guidance to Eliminate Saphenous Varicose Vein Reflux; A 2-year followup. Dermatol Surg 2002; 28: 38-42
2. Minn RJ, Kilnani N, Zimmet SE: Endovenous laser treatment of saphenous vein reflux: long-term results. JVIR 2003;14:991-996
3. Minn RJ, Khilnani NM, Golia P:Duplex Ultrasound Evaluation of Lower Extremity Venous Insufficiency. JVIR 2003 14:1233-1241
4. Feied C: Varicose Veins. emedicine.com 5. Perkowski P, Rajoagopalan R, Gowda RC, et al: Endovenous Laser Ablation of the Saphenous Vein for Treatment of Venous Insufficiency and Varicose Veins: Early Results From a Large Single-Center Experience. J Endovasc Ther 2004;11:132-138.
6. Feied C: Varicose Veins. emedicine.com
7. Pichot O, Sessa C, Chandler JG, et al: Role of Duplex Imaging in Endovenous Obliteration for Primary Venous Insufficiency. J Endovasc Ther 2000;7:451-459.
8. Feied C: Varicose Veins. emedicine.com
9. Weiss RA, Feied CF, Weiss MA. Vein Diagnosis and Treatment,McGraw-Hill, New York, 2001.

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